Comparison of Quality Characteristics of Selected Yellow-and White-fleshed Peach Cultivars

Physical, chemical and sensory characteristics and volatile constituents of five yellow-and six white-fleshed peach cultivars were compared. The soluble solids/titratable acidity ratios were significantly higher and the Minolta “b” values were significantly lower for white-fleshed than for yellow-fleshed cultivars. Shelf life of white-fleshed fruit equalled that of yellow-fleshed fruit. Amounts of five compounds that contribute significantly to typical peach aroma were significantly higher in white-fleshed than in yellow-fleshed peaches. Generally, flesh color showed little influence on hedonic scores, peach impact and sweet/sour balance.     

POSTHARVEST QUALITY AND SENSORY ATTRIBUTES OF ‘BYRONGOLD’ AND ‘RUBYSWEET’ PLUMS1

Fruit from two new cultivars of plums, ‘Byrongold’ and ‘Rubysweet’ were harvested at three maturities. Maturity one and two were ripened for three and six days at 20C and 85% relative humidity to determine fruit quality characteristics during storage. Plums were separated into three maturity categories by delayed light emission. Fruit size, weight, hue angle, flesh firmness, soluble solids and concentration of sugars, organic acids and sensory attributes were determined to evaluate stroage quality of the fruit. Significant differences were found between cultivars for sucrose, glucose, fructose and sorbitol. Sugar concentrations varied within the same cultivar by maturity and storage times. In general, acid levels decreased as plums ripened. Panelists preferred “Byrongold” ripened for three days for tartness and juiciness and “Byrongold” ripened for six days for sweetness. “Rubysweet” ripened for three days was preferred for sweetness, tartness and juiciness. Significant differences were found in peel bitterness between cultivars and days ripened. Unripened maturity 2 ‘Byrongold’ and unripenedd maturity 3 ‘Rubysweet’ had the highest peel bitterness. Hedonic scores showed ‘Rubysweet’.     

BOOK REVIEWS

HEAT TRANSFER AND FOOD PRODUCTS. Bengt Hallström, Christina Skjölderbrand and Christian Trägårdh. Elsevier Applied Science Publishers, London and New York. 1988. pp. xiv + 263.
FLAVOUR ENCAPSULATION. (S. J. Risch and G. A. Reineccius, eds.) ACS Symposium Series 370, ACS, Washington D.C., 1988, 202 pp. $54.95 U.S. and Canada $65.95 Elsewhere.
POSTHARVEST PHYSIOLOGY OF VEGETABLES. (J. Weichmann, ed.) Marcel Dekker, New York and Basel. 1987. 597 pp. $150 U.S. and Canada, $180 all other countries.
PROGRESS AND TRENDS IN RHEOLOGY II. (editors H. Giesekus, M. F. Hibberd, P. Mitschka, P. Riha and J. Sestak, eds.) Steinkopf-Verlag, Darmstadt, Springer-Verlag, New York. 502 pp. DM 280.
HPLC IN FOOD ANALYSIS. (R. Macrae, ed.) Academic Press, London, 493 pp. $77.50 U.S. £55 elsewhere.
WATER ACTIVITY: THEORY AND APPLICATIONS TO FOODS. (L. B. Rockland and L. R. Beuchat, eds.) Marcel Dekker, New York 1987. ISBN 0-8247-7759-X; 404 pp.; $59.75 in the U.S. and Canada; $71.50 elsewhere.
GUMS AND STABILISERS FOR THE FOOD INDUSTRY. (G. O. Phillips, D. J. Wedlock and P. A. Williams) IRL Press, Oxford and Washington, 560 pp. £50 U.S. $100.
SAVOURY COATINGS. (D. B. Fuller and R. T. Parry, eds.) Elsevier Applied Science Publishers, New York. 130 pp., 1988. $47.00.
TOTAL QUALITY ASSURANCE FOR THE FOOD INDUSTRIES. W. A. Gould and R. W. Gould. CTI Publications, Baltimore. 1988. 394 pp. $50 in the U.S. $65 overseas.     

COMPREHENSIVE,THEORETICALLY BASED,CORRELATING EQUATIONS FOR FREE CONVECTION FROM ISOTHERMAL SPHERES

Correlating equations are developed for the local and mean Nusselt number for free convection from an isothermal sphere as a function of the Rayleigh and Prandtl numbers. These expressions are based primarily on theoretical solutions for limiting cases, and hence are presumed to be more reliable than purely empirical correlations. The predictions of the proposed expressions are, however, validated by comparisons with prior experimental data. The expressions for the mean Nusselt number are shown to be applicable for all Ra and Pr. The expressions for the local Nusselt number are limited in applicability to the laminar boundary layer regime. The same equations are applicable to mass transfer and to combined heat and mass transfer in terms of the Sherwood, Schmidt and appropriately modified Rayleigh numbers.     

Reverse Monte Carlo reconstruction algorithm for discrete electron tomography based on HAADF‐STEM atom counting

In this paper, we propose an algorithm to obtain a three‐dimensional reconstruction of a single nanoparticle based on the method of atom counting. The location of atoms in three dimensions has been successfully performed using simulations of high‐angle‐annular‐dark‐field images from only three zone‐axis projections, [110], [310] and [211], for a face‐centred cubic particle. These three orientations are typically accessible by low‐tilt holders often used in high‐performance scanning transmission electron microscopes.     

Ripening and Cold Storage Changes in the Quality Characteristics of Nonmelting Clingstone Peaches (FLA 9-20C)

Minolta “a” values, SS/TA ratio, sucrose, total sugar contents, and sweet sensory scores increased significantly with increased degree of maturity of unripened peaches. Firmness, Minolta “L” values, hue angle, TA, sorbitol, green and sour flavor attributes, and peach complex and fruity/ester aromas decreased significantly with maturity. Maturity 1 and 2 peaches stored for 8 wk at 0° C and subsequently ripened showed no significant change in physical characteristics except for firmness which increased at 8 wk storage. Maturity 1 and 2 peaches could be ripened at 20° C for up to 15 days and stored at 0° C for 8 wk without notable change in quality.     

Saturation Factors for Calcium Hydroxide and Calcium Sulfates in Fresh Portland Cement Pastes

Aqueous extracts from five cement pastes at w/c = 0.5 were analyzed for Ca²⁺, SO^2–₄, Na⁺, and K⁺. Degrees of saturation with respect to portlandite, gypsum, and syngenite were determined at ages from 6 min to 3 h, taking into account ionic association effects. Portlandite saturation is usually attained within a few minutes of mixing, but rates of saturation vary. The maximum degree of saturation is 2 to 3 times the equilibrium value and is attained within 2 h. Initial super-saturation with respect to gypsum, and in some cases syngenite, occurs at very early ages and declines to the saturation level within 12 min. Results are interpreted by use of a solution-precipitation model for cement hydration. The calculated critical size of portlandite nuclei at early ages is ∼0.1 μm. Slow growth of portlandite nuclei suggests a surface poisoning phenomenon.     

Special Issue: Quantum Interference

A general theory of optical image evaluation seems now to be within reach of investigation as a result of the introduction into this field of the powerful methods of Fourier analysis. The most important practical application of such a theory is to the quality evaluation of optical systems. To be realistic, such a quality evaluation must be defined relative to the statistical properties of a prescribed object set and a prescribed receiving surface. A simplification results from the fact that, in the majority of applications, the quality of a high-grade optical system can be satisfactorily assessed by its power to reproduce low-contrast fine detail. This leads to the idea of assessing the system by means of its averaged performance on low contrast random object sets occupying isoplanatism patches in different parts of the field. As is well-known, fine detail is in general reproduced in a metamorphosed form, which however can usually be interpreted correctly by a practised operator. Two distinct types of quality evaluation result according as we demand that the image shall resemble the object as closely as possible, or that it shall give the maximum amount of information about the object without regard to the amount of work (image interpretation) which may be needed to extract this information. In the second type of evaluation, an essentially unique evaluation of image quality exists, viz. that based on the mean information content of the images of a prescribed low-contrast object set; in the first, there is no unique evaluation, but a number of different evaluations of image quality can be made, each of which leads to a corresponding quality evaluation for the optical system. An exploratory study of the relative merits of these evaluations, and of thier interrelations, seems to be an urgent task for the theoretical optician. A beginning to this study is attempted in the present paper. Three simple and natural assessments of the first type are considered, and it is shown that in small-field systems the third assessment (correlation quality) is related in an interesting way to a generalised form of Strehl definition. For such systems, the first assessment (relative structural content) is known to agree with assessment by information content in the limiting case of a random object set whose images are almost completely smothered in random noise. The second assessment (fidelity) is connected with the other two by a simple mathematical relation. The discussion includes consideration of the effects of image spread and noise in the receiving surface. Il paraît maintenant possible de commencer à bâtir une théorie générale de la qualité des images optiques, du fait de l'introduction dans ce domaine des méthodes puissantes de l'analyse de Fourier. L'application pratique la plus importante d'une telle théorie est la détermination de la qualité des systèmes optiques. Pour être réaliste, une telle évaluation de qualité doit être définie à partir de propriétés statistiques d'ensembles d'objets et des propriétés d'une surface réceptrice donnée. Une simplification résulte du fait que, dans la majorité des applications, la qualité des bons systèmes optiques peut être déterminée de façon satisfaisante par leur aptitude à reproduire de petits détails de faible contraste. Ceci conduit à l'idée d'évaluer la qualité d'un système à l'aide de la moyenne des résultats obtenus sur des objets aléatoires de faible contraste occupant des régions isoplanétiques dans différentes parties du champ. Il est bien connu que les fins détails subissent généralement une transformation, mais qu'un observateur entraîné peut souvent les interpréter correctement. Deux types de méthodes d'estimation de la qualité en résultent, suivant que l'on demande que l'image ressemble à l'objet d'aussi près que possible, ou que l'on obtienne le maximum d'information sur l'objet, sans tenir compte de l'importance du travail d'interprétation qui peut être nécessaire pour extraire cette information. Dans le deuxième cas une évaluation unique existe: celle qui est basée sur le calcul de la quantité moyenne d'information dans les images d'un ensemble donné d'objets de faible contraste. Dans le premier cas, il n y a pas d'évaluation unique, mais un certain nombre de méthodes peuvent être employées, chacune conduisant à une évaluation de la qualité du système optique. Une étude des mérites relatifs de ces critères et de leurs relations paraît s'imposer au théoricien. On présente dans l'article ci-dessous, le début d'une telle étude. Trois critères naturels et simples (appartenant à la première catégorie) sont envisagés et l'on montre que dans les systèmes à faible champ le 3 e critère (critère de corrélation) est relié de façon intéressante à une forme généralisée du critère de Strehl. Pour de tels systèmes, on sait que le premier critère (évaluation du ‘ contenu structural ’) s'accorde avec celui qui résulte du calcul de l'information dans le cas limite d'un ensemble d'objets aléatoires dont les images sont presque complètement masquées par le bruit. Le second critère (fidélité) est relié aux deux autres par une relation mathématique simple. La discussion tient compte des effets de la diffusion de l'image et du bruit introduits par la surface réceptrice. Dank der leistungsfähigen Methode der Fourier analyse scheint es jetzt möglich zu sein, eine allgemeine Theorie für die Beurteilung der Bildgüte aufzustellen. Die wichtigste praktische Anwendung einer solchen Theorie richtet sich auf die Leistungsbewertung optischer Systeme. Um in einem realen Rahmen zu bleiben, muss sich diese Leistungsbewertung auf die statistischen Eigenschaften einer vorgegebenen Objektmenge und einer festgelegten Auffangfläche beziehen. Eine Vereinfachung ergibt sich aus dem Umstand, dass bei der Mehrzahl der Anwendungen die Leistung eines wohlkorrigierten optischen Systems hinreichend gut durch seine Wiedergabe kontrastarmer Einzelheiten beurteilt werden kann. Das führt auf den Gedanken, ein optisches System nach der durchschnittlichen Wiedergabe zufälliger kontrastarmer Feinstrukturen in den verschiedenen Isoplanasiebereichen des Gesichtsfeldes zu beurteilen. Bekanntlich wird feines Detail im allgemeinen in einer veränderten Form wiedergegeben, die jedoch gewöhnlich von einem erfahrenen Beobachter richtig gedeutet werden kann. Es ergeben sich zwei verschiedene Arten der Gütebeurteilung eines Bildes, je nachdem ob man verlangt, entweder, dass das Bild dem Objekt möglichst ähnlich ist, oder, dass es den grössten Informationsgehalt berü das Objekt liefert, ohne Rücksicht auf den dabei erforderlichen Arbeitsaufwand (Bilddeutung). Bei der zweiten Art der Qualitätsabschätzung gibt es eine im wesentlichen eindeutige Bewertung der Bildgüte, nämlich diejenige, die auf dem mittleren Informationsinhalt der Bilder einer statistisch vorgeschriebenen Menge kontrastarmer Objekte beruht. Die erste Art jedoch bringt keine eindeutige Bewertung, sondern man kann eine Anzahl verschiedener Bildgütekriterien aufstellen, von denen jede zu einer entsprechenden Gütebewertung des optischen Systems führt. Die Untersuchung der jeweiligen Vorzüge dieser Bewertungen und ihrer gegenseitigen Beziehungen scheint für den theoretischen Optiker eine dringende Aufgabe zu sein. Einen Anfang dazu soll die vorliegende Arbeit geben. Es werden drei einfache und naheliegenden Gütekriterien der ersten Art betrachtet. Es zeigt sich, dass das dritte davon (Korrelationsgüte) bei Systemen mit kleinem Ges ichtsfeld in eigenartiger Weise mit einer verallgemeinerten Form der Strehlschen Definitionshelligkeit in Verbindung steht. Für solche Systeme ist bekanntlich das erste Kriterium (relativer Strukturinhalt) im Grenzfall in Übereinstimmung mit der Beurteilung nach dem Informationsinhalt, wenn man sich auf zufällige Objektmengen beschränkt, deren Bilder fast vollständig in den statistischen Schwankungen (noise) untergehen. Das zweite Kriterium (Objekttreue) steht zu den beiden anderen in einer einfachen mathematischen Beziehung. Schliesslich wird noch der Einfluss der Bildverbreiterung und der statistischen Schwankungen in der Auffangfläche betrachtet.     

Na+ Binding as Measured by 23Na Nuclear Magnetic Resonance Spectroscopy Influences the Perception of Saltiness in Gum Solutions

Binding of Na⁺ in aqueous gum systems as determined by ²³Na nuclear magnetic resonance (NMR) spectroscopy and its relations to perceived saltiness were examined. Two levels of NaCl (0.1% and 0.2%) were added to two concentrations (0.1% and 0.3%) of two ionic (xanthan and kappa carrageenan) and two non-ionic (locust bean and guar) gum solutions. Saltiness perception was affected by the ionic properties of the gums. NMR transverse relaxation rates (R₂, see^?l) indicated Na⁺ was less mobile in ionic than nonionic systems. Ionic gums correspondingly suppressed saltiness perception- compared to nonionic gums. As Na⁺ increased in both ionic and nonionic systems, R₂ values converged and perceived saltiness equalized. Food components that bind Na⁺ may suppress saltiness perception, which may be important in low-sodium foods.     

Estimating suspended sediment concentrations from spectral reflectance data

Abstract

A method for estimating sediment concentrations at different depths in coastal waters from measured spectral reflectance above the sea is proposed. The water backscattering coefficient is obtained by integrating a scattering cross section derived from Mie theory over a Junge type particle-size distribution. The results for turbid water, near an arid coast, with vertical mixing, shows a maximum of particle concentration in the middle layer, while the same method applied to reflectance data for ‘blue’ water, gives a relative concentration of sediment that gradually increases with depth.